The NHL playoffs are aboutseeing the job through. They require a grinder's mentality and a finisher's touch.

And quite often, they are about endurance. Not just through four rounds of a best-of-seven series, but through multiple overtime periods.

Coach John Stevens got his first taste of double OT tonight at the Wachovia Center when the Flyers beat the Washington Capitals, 4-3, on Mike Knuble's goal 6 minutes, 40 seconds into the second extra session.

The victory gave the Flyers a three-games-to-one stranglehold on the series, which could end tomorrow in Washington.

"If I'm not around the net, I don't have much chance scoring goals," Knuble said. "That's my identity as a player. Some days, they come to you and some they don't. . . . What a huge thrill just to hear the building explode. It's an unbelievable feeling. You wish you could bottle it up for next time."

In the second OT, the Flyers had several tips in front of the net without scoring. Joffrey Lupul buried one shot in goalie Cristobal Huet's pads off the rush.

The Flyers had trailed, 3-2, about halfway through the third period when Huet made a spectacular diving save across the crease to deflect Scottie Upshall's shot with his glove hand. The puck was headed for an empty net.

Seconds later, the Caps were hit with a penalty for too many men on the ice, and Flyers center Danny Briere tied the score with his team-high fifth goal of the playoffs.

Flyers goalie Marty Biron made a critical glove snare of David Steckel's drive in the slot with less than six minutes to go in regulation. Three minutes later, Biron made a pad stop on Viktor Kozlov, who had stripped Braydon Coburn of the puck on the breakout. Kozlov was called for goaltender's interference because momentum had carried him into Biron.

In the first overtime, Biron made a marvelous save on an Alexander Semin shot off a draw with 7:15 left in what had become pond hockey. R.J. Umberger had several chances to end it and couldn't. Both Jeff Carter, who scored two goals in regulation, and Upshall missed a loose puck in the slot that could have ended it with 5:14 remaining.

Center Mike Richards nearly knocked himself out in a collision with Semin and the side board in the final three minutes.

Several things stood out in this one. First, the Capitals had their most aggressive start of the series. Second, the Flyers continued to have problems with their power play, which was second in the league during the regular season. It was 1 for 7 after three periods.

Also, the ice seemed poor, perhaps because yesterday was the warmest day of spring at 70 degrees.

But the most impressive difference was Capitals coach Bruce Boudreau's moving Alexander Ovechkin off the point on the power play, into the low slot. The result? The Russian winger had two power-play assists in the first period.

As good as the Caps' start was, the Flyers' was better. Carter scored his first goal on the opening shift, 42 seconds into the game. Upshall did yeoman's work to dig the puck off the boards and get it to Knuble.

Knuble's centering pass into the slot should have been picked off by Washington winger Donald Brashear, but it wasn't. Carter got the puck, then backhanded it into the corner of the net.

On the next shift, Vinny Prospal and Steve Eminger got into a fracas, and it triggered a major scrum, resulting in a Caps power play. Neither Prospal nor Eminger went to the penalty box, although they had traded punches.

Washington scored on the power play at 2:41 as Ovechkin made a deft pass from below the goal line to a wide-open Nicklas Backstrom below the opposite circle. The Swede had a lot of net to shoot at.

Before the period ended, the Caps briefly had twice as many power-play goals in the series (four) as the Flyers.

Washington had a five-on-three man advantage for 1:48 thanks to two careless slashing penalties, one by Briere, the other by Derian Hatcher. Semin made the Flyers pay on the first with a game-tying goal off a nice feed from Backstrom.

Carter retied the game at 18:33 just as a Flyers power play expired. You don't often read about Jaroslav Modry making a great pass on the power play, but the veteran Czech defenseman looked through a crowd in front at the right circle and saw Carter free at the other circle. Carter took the pass, waited for goalie Huet to go down, then lifted it over him. It was his third goal in the series.

"The first goal was a turnover by them," Carter said. "Knubes made a great play and I was lucky to get it on net. The second goal was set up with great pass by 'Mo'. I just kind of snuck in the far side there and I had a wide-open net."

Biron yielded a soft goal to Eminger early in the second period as Washington regained the lead, 3-2. Again, instead of standing straight up and making himself big to take away the short side, Biron was on his knee when Eminger fired a bouncing puck from the right circle off Jason Smith's backside, inside the post.

Biron made it up for it in the first OT.

Contact staff writer Tim Panaccio at 215-854-2847 or tpanaccio@phillynews.com.